University  of  Illinois 

Library  at 

Urbana-Champaign 
ACES 


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UNIVERSITY  OF  ILLINOIS 


Agricultural  Experiment  Station 


BULLETIN  No.  125 


THIRTY  YEARS  OF  CROP  ROTATIONS 
ON  THE  COMMON  PRAIRIE  SOIL  OF  ILLINOIS 


BY  CYRIL,  G.  HOPKINS,  J.  E.    READHIMER 
AND  WM.  G.  ECKHARDT 


UKBANA,  ILLINOIS,  MAY,  1908 


SUMMARY  OF  BULLETIN  No.  125 

1.  Authentic  records  show  that  our  oldest  soil  experiment   fields  were 
established  at  the  University  of  Illinois  in  1879.  Page  327 

2.  Under  one  system  of  farming-  the  yield  of  corn  has  decreased  from 
70  bushels  to  27  bushels  per  acre  within  thirty  years;  while  under  another 
system  the  yield  of  corn  has  increased  to  96  bushels  per  acre  as  an  average . 

Page  324 

3.  The  fertility  of  the  soil  can  be  maintained,  or  even  increased,,  by  a 
proper  system  of  grain  farming  with  legumes  in  rotation.  Page  325 

4.  A   good   system   of  live  stock  farming,  which  may  or  may  not  be 
more  profitable  than  grain  farming,  will  also  maintain  the  fertility  of  the 
soil.  Page  326 

5.  Farm  manure  has  given  a  net  profit  in  the  first  three  crops  of  $1.30 
per  ton,  or  of  $7.80  an  acre  when  six  tons  have  been  applied.  Page  341 

6.  As  an  average  of  18  tests,  covering  three  years,  with  a  rotation  of 
corn,  oats,  and  clover,  the  use  of  75  pounds  of  phosphorus  has  produced  in- 
creases in  crop  yields  worth  $12.39.  Page  342 

7.  L/arger  crop  yields  have  been   secured    (and  phosphorus   has  been 
nearly  twice  as  effective)  in  a  three-year  rotation  of  corn,  oats,  and  clover, 
than  in  a  two-year  rotation  of  corn  and  oats.  Page  346 

8.  While  phosphorus  is  commonly  the  element  that  first  limits  the  yields 
of  crops  on  our  common  soils,  nitrogen  is  lost  from  the  soil  so  much  more 
rapidly  under  poor  systems  of  farming  that  nitrogen  soon  becomes  the  limit- 
ing element,  after  which  phosphorus  alone  has  no  power  to  increase  the  crop 
yields.  Page  353 

9.  This    bulletin  will   be  sent  free  of   charge   to   anyone  interested  in 
Illinois  agriculture,  upon  request  to  E.  Davenport,  Director  Agricultural  Ex- 
periment  Station,    Urbana,  Illinois,  and  if  so  requested,  the  name  of  the 
applicant  will  be  placed  upon  the  permanent  mailing  list  of  the. Experiment 
Station,  so  that  all  subsequent  bulletins  will  be  sent  to   him  as   they  are 
issued. 


THIRTY  YEARS  OF  CROPUROTATIONS  ON 
THE    COMMON   PRAIRIE    SOIL  OF    ILLINOIS 

BY  CYRIL,  G.  HOPKINS,  CHIEF  IN  AGRONOMY  AND  CHEMISTRY, 
J.  E.  READHIMER,  SUPERINTENDENT  OF  SOIL  EXPERIMENT  FIELDS,  AND 

WM.   G.   ECKHARDT,  ASSISTANT  IN  Soil,  FERTILITY 

Near  the  end  of  thirty  years  an  average  yield  of  96  bushels  of 
corn  per  acre  on  one  field,  and  an  average  yield  of  27  bushels  of 
corn  per  acre  on  another  field,  must  be  accepted  as  the  results  of 
different  systems  of  farming  on  land  that  was  similar  and  uniform 
at  the  beginning.  These  results  have  been  obtained  in  the  heart 
of  the  corn  belt  and  on  typical  Illinois  prairie  land,  representing  the 
most  extensive  and  the  most  important  type  of  soil  in  the  state,— 
land  whose  present  market  value  ranges  from  $150  to  $200  per 
acre, — a  value  that  may  change  rapidly  in  Illinois,  as  it  has  already 
changed  in  the  older  states. 

The  96  bushels  is  the  average  yield  per  acre  for  the  years  1905, 
1906,  and  1907,  in  one  system  of  farming;  and  the  27  bushels  is 
the  average  yield  for  the  same  years  in  another  system  of  farming 
on  land  originally  the  same.  Between  these  extremes  other  results 
have  been  obtained  from  several  other  systems  of  farming. 

It  is  the  purpose  of  this  bulletin  to  report,  especially  to  Illinois 
landowners  and  farmers,  the  valuable  data  that  have  been  secured 
in  these  investigations.  The  results  from  these  experiment  fields 
are  now  beginning  to  influence  the  agricultural  practice  of  the 
state,  and  they  are  destined  to  be  of  inestimable  value  to  the  com- 
monwealth. Before  discussing  the  details  of  the  work,  a  compre- 
hensive summary  of  the  effects  of  the  different  systems  of  farming 
will  be  considered. 

SYSTEMS  OF  FARMING 

In  Table  i  are  given  three-year  averages  of  the  yields  of  corn 
secured  in  recent  years,  including  1907,  which  is  the  29th  year  of 
the  oldest  experiments  and  the  i3th  year  of  a  newer  and  more  ex- 
tensive series  of  experiments  with  crop  rotations  and  soil  treatment 
with  special  reference  to  two  markedly  different  systems  of  farm- 

323 


324 


BULLETIN  No.  125. 


[May, 


ing,  of  which  one  is  termed  grain  farming  and  the  other  live  stock 
farming.  (Some  preliminary  cropping  and  other  variations  from 
the  systems  indicated  are  reported  in  the  detailed  discussion  and 
tabular  statements  in  the  following  pages.)  The  crops  in  the  3Oth 
year  of  the  older  experiments  may  be  seen  by  visiting  these  fields 
during  the  season  of  1908. 

TABLE  1. — LATEST  CORN  YIELDS  PROM  THE  UNIVERSITY  off  ILLINOIS  EX- 
PERIMENT FIELD  AT  URBANA:    TYPICAL  CORN  BELT  PRAIRIE  SOIL 
(Three-year  averages:     Bushels  per  acre) 


Crop 
years. 

Crop  system. 

13-year 
experiments. 

29-year 
experiments. 

1905  -6  -7 

Corn  every  year.  .'  

35  bu. 

27  bu. 

1903  -5  -7 

62    " 

46    " 

1901,-4,-7 

Corn,  oats,  clover  

66    " 

58    " 

Average  of  Three  Corn  Crops  in  Corn-Oats-Clover  Rotation: 
13-Year  Experiments 


Crop 
years. 

Special  treatment. 

Grain 
farming- 
(with  legumes*)  . 

Live  stock 
farming- 
(with  manuref). 

1905  -6  -7 

None. 

d't   lin 

81  bu 

1905  -6  -7 

Lime. 

72     " 

85    " 

1905,  -6,  -7 

Lime, 

phosphorus  

90    " 

93    " 

1905,  -6,-7 

Lime, 

phosphorus,  potassium.  .  . 

94    " 

96    " 

*Legume  catch  crops  and  crop  residues. 

fManure  applied  in  proportion  to  previous  crop  yields. 

As  an  average  of  the  last  three  years  where  corn  has  been 
grown  every  year  the  yield  has  been  27  bushels  in  the  29-year  ex- 
periments and  35  bushels  in  the  1 3-year  experiments.  The  lesson 
of  these  experiments  is  that  12  years  of  cropping  where  corn  fol- 
lows corn  every  year  reduces  the  yield  from  more  than  70  bushels 
to  35  bushels  per  acre,  after  which  the  decrease  is  much  less  rapid, 
amounting  to  only  8  bushels  reduction  during  the  next  16  years. 
Undoubtedly  the  rapid  reduction  during  the  first  12  years  of  con- 
tinuous corn  growing  is  due  in  large  part  to  the  destruction  of  the 
more  active  decaying  organic  matter,  resulting  ultimately  in  insuf- 
ficient liberation  of  plant  food  within  the  feeding  range  of  the 
corn  roots.  In  addition  to  this,  the  development  of  corn  insects  in 
soil  on  which  their  favorite  crop  is  grown  every  year  is  sometimes 
an  important  factor  in  reducing  the  yield. 

Where  corn  is  followed  by  oats  in  a  two-year  rotation  the  av- 
erage yield  of  the  last  three  crops  of  corn  is  46  bushels  in  the  29- 


1908.]  THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS.  325 

• 

year  experiments,  whereas  in  the  1 3-year  experiments  the  average 
yield  for  the  same  three  years  is  62  bushels  of  corn  per  acre.  In 
this  case  the  destruction  of  humus  is  less  rapid,  and  the  develop- 
ment of  the  corn  insects  is  discouraged  by  changing  to  oats  every 
other  year,  so  that  the  decrease  in  yield  is  less  marked  during  the 
early  years,  although  the  reduction  continues  persistently  with 
passing  years.  During  the  first  n  years  the  yield  decreased  from 
more  than  70  bushels  to  62  bushels,  and  during  the  next  16  years 
a  further  reduction  of  16  bushels  has  occurred. 

With  the  three-year  rotation  corn  is  grown  for  one  year,  fol- 
lowed by  oats  with  clover  seeding  the  second  year,  and  clover  alone 
the  third  year.  During  the  first  10  years  under  this  system  the 
yield  of  corn  has  decreased  from  more  than  70  bushels  to  66,  and 
during  the  next  16  years  the  yield  has  further  decreased  to  58  bush- 
els, the  average  reduction  being  only  one-half  bushel  a  year.  In 
this  system  the  most  marked  reduction  in  crop  yields  has  not  yet 
appeared,  although  it  must  be  expected  in  the  future  because  the 
clover  crop  is  already  beginning  to  fail  on  the  oldest  field  even  in 
seasons  when  clover  succeeds  well  on  newer  land  under  the  same 
crop  rotation.  When  clover  fails  we  substitute  cowpeas  for  that 
year  on  that  field,  which  thus  provides  a  legume  crop  and  preserves 
the  three-year  rotation.  Further  time  is  required  to  determine 
how  much  the  cowpeas  will  help  to  lessen  the  rate  of  decrease  in 
yield  of  corn  and  oats. 

GRAIN  FARMING 

In  the  lower  part  of  Table  I  (third  column)  are  recorded  the 
average  yields  of  corn  for  the  last  three  years  in  a  system  of  grain 
farming,  in  a  three-year  rotation  of  corn,  oats,  and  clover.  This 
system  when  fully  under  way  provides  that  the  corn  shall  be  husked 
and  the  stalks  disked  down  in  preparation  for  the  seeding  of  oats 
and  clover  the  second  year.  In  harvesting  the  oats  as  much  straw 
as  possible  is  left  in  the  stubble,  which  may  be  mowed  later  in  the 
summer  to  prevent  the  seeding  of  the  clover  or  weeds.  In  the 
spring  of  the  third  year  the  clover  is  mowed  once  or  twice  be- 
fore the  usual  haying  time  and  left  lying  on  the  land.  The  seed 
crop,  if  successful,  is  harvested  with  a  hay  buncher  attached  to  the 
mower  or  in  any  other  way  to  avoid  raking,  and  afterward  the 
threshed  clover  straw  is  returned  to  the  land,  all  of  this  accumu- 
lated organic  matter  to  be  plowed  under  for  the  following  corn 
crop,  which  begins  the  next  rotation.  In  addition  to  this,  catch 
crops  of  annual  legumes,  such  as  cowpeas,  may  be  seeded  in  the 
corn  at  the  time  of  the  last  cultivation  and  disked  in  the  next  spring 


326  BULLETIN  No.   125.  [May, 

» 

with  the  corn  stalks.  If  biennial  or  perennial  legumes  are  used  as 
catch  crops,  the  corn  ground  may  be  plowed  for  oats. 

The  corn  yields  reported  for  this  system  in  Table  I  were  se- 
cured where  the  system  was  not  fully  under  way,  the  legume  catch 
crops  being  the  only  organic  matter  returned  to  the  soil,  aside  from 
the  residues  necessarily  left  from  the  corn-oats-clover  rotation.  By 
using  three  different  fields  for  this  rotation,  every  crop  may  be 
grown  every  year,  and  the  yields  of  corn  reported  are  true  three- 
year  averages. 

With  no  special  soil  treatment  aside  from  the  use  of  legume 
catch  crops,  the  yield  of  corn  for  1905,  1906,  and  1907  averaged 
69  bushels.  Where  the  equivalent  of  ^  ton  per  acre  of  ground 
limestone  was  applied  five  years  ago  the  corn  has  yielded  72  bush- 
els per  acre ;  and,  with  phosphorus  added  for  six  years  at  the  rate 
per  annum  of  25  pounds  per  acre  of  the  element  phosphorus  (in 
200  pounds  of  steamed  bone  meal)  the  average  yield  of  corn  has 
been  90  bushels  per  acre  for  the  last  three  years.  The  yearly  addi- 
tion of  42  pounds  of  potassium  in  100  pounds  of  potassium  sulfate 
has  further  increased  the  yield  to  94  bushels. 

The  cost  per  ton  delivered  is  about  $2  for  the  limestone,  $25 
for  the  steamed  bone  meal,  and  $50  for  the  potassium  sulfate. 

LIVE  STOCK  FARMING 

Under  the  heading  "Live  Stock  Farming"  in  Table  i  are  re- 
corded the  average  yields  of  corn  secured  during  the  last  three 
years  where  farm  manure  has  been  applied  to  the  clover  ground 
to  be  plowed  under  for  corn.  The  plan  of  this  system  is  to  remove 
all  crops  from  the  land  as  usually  harvested,  including  the  corn  and 
stover,  oats  and  straw,  and  both  first  and  second  crops  of  clover. 
The  amounts  of  manure  applied  to  the  different  plots  are  deter- 
mined by  the  crop  yields  secured  during  the  previous  rotation. 
While  the  system  of  cropping  followed  during  the  past  13  years  on 
these  plots,  and  on  those  just  described  under  "grain  farming,"  has 
been  approximately  equivalent  to  a  three-year  rotation  of  corn, 
oats,  and  clover,  the  applications  of  manure  have  been  made  only 
for  the  three  years,  1905,  1906,  and  1907.  If  the  average  yields 
are  decreasing  on  plots  that  receive  only  the  amounts  of  manure 
that  can  be  produced  in  practice  from  the  crops  grown,  then  the 
applications  of  manure  must  also  be  reduced  on  such  land ;  where- 
as if  the  crop  yields  are  increasing  where  both  manure  and  phos- 
phorus are  applied,  then  the  applications  of  manure  for  such  plots 
may  be  increased  in  direct  proportion. 


iooS.]  THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS.  327 

Where  manure  alone  has  been  used  in  this  rotation  the  corn  has 
averaged  81  bushels  per  acre  for  the  last  three  years;  with  lime 
added  the  average  is  85  bushels;  with  lime  and  phosphorus  the 
manured  land  has  averaged  93  bushels  of  corn,  and  this  was  in- 
creased to  96  bushels  by  adding  potassium. 

While  potassium  has  usually  made  some  increase  in  crop  yields 
on  these  fields  it  has  not  nearly  paid  its  cost.  The  most  profitable 
yields  are  the  9O-bushel  average  in  the  grain  farming  or  the  93- 
bushel  average  in  the  live  stock  system.  The  effect  of  limestone  has 
not  yet  been  sufficiently  uniform  to  recommend  its  use  on  this  soil, 
but  marked  profit  has  resulted  from  the  addition  of  phosphorus, 
which  is  applied  in  sufficient  amount  actually  to  enrich  the  land  and 
not  as  a  stimulant. 

HISTORY  OF  THE  OLD  EXPERIMENT  FIELD 

It  appears  that  the  oldest  soil  experiment  field  in  the  United 
States  with  an  authentic  record  of  its  origin  and  with  a  present 
continuation  of  the  experiments  originally  inaugurated  is  on  the 
campus  of  the  University  of  Illinois,  or  rather  it  is  surrounded  by 
the  University  campus.  In  the  biennial  report  for  1879  and  1880, 
on  page  232,  and  under  date  of  March  10,  1880,  is  the  following: 

"The  Farm  Committee  then  submitted  the  following  report: 
To  the  Hon.  Board  of  Trustees  of  the  Illinois  Industrial  University: 

"Your  committee  beg-  leave  to  submit  the  following  recommendations 
from  the  Professor  of  Agriculture,  in  regard  to  experiments  for  the  coming 
season: 

"Fifth — The  formal  commencement  of  what  is  designed  to  be  a  long  con- 
tinued experiment  to  show  the  effect  of  rotation  of  crops,  contrasted  with 
continuous  corn  growing — with  and  without  manuring,  and  also  the  effect 
of  clover  and  grass  in  a  rotation.  A  commencement  was  made  last  year, 
and  we  are  fortunate  in  having  a  piece  of  land  more  than  usually  well  adapted 
for  such  a  test. 

"The  report  was  approved,  and  its  recommendation  concurred  in." 

Thus,  these  oldest  rotation  experiments,  begun,  according  to 
the  official  records,  by  Professor  George  E.  Morrow,  in  1879,  wMl 
complete  a  record  of  thirty  years  in  1908. 

In  Bulletin  No.  13  of  the  Illinois  Agricultural  Experiment  Sta- 
tion, published  in  1901  and  signed  by  Professor  Morrow,  the  state- 
ment is  made  that  from  the  beginning  of  these  experiments  plot 
No.  3  had  "been  in  corn  continuously,"  that  plot  No.  4  had  been 
"in  corn  and  oats  alternately,"  and  that  plot  No.  5  had  "had  this 
rotation:  Corn,  2  years;  oats,  I  year;  meadow  (clover,  timothy, 
or  both)  3  years."  The  records  also  state  that  these  plots  had  re- 
ceived "no  manure  or  commercial  fertilizers  of  any  kind." 


328 


BULLETIN  No.  125. 


[May, 


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PLATE  1.—  DIAGRAM  (DRAWN  TO  SCALE)  OF  THE  URBANA  SOIL  EXPERIMENT  FIELDS,  SHOWING  THE  OLD  FIELD  SOUTH  OF  THE 
OBSERVATORY,  AND  ALSO  THE  SEVEN  SERIES  OF  TEN  PLOTS  EACH  LYING  EAST  OF  MATHEWS  AVENUE. 

The  photographs  shown  on  the  opposite  page  were  both  taken  from  the  same  point.  The  lower  view  looking  southwest  shows  the 
oldest  plots  on  the  right  and  series  100  on  the  left,  with  Mathews  avenue  between  and  farm  buildings  in  the  background.  The  upper 
vie.w  looking  southeast  shows  plainly  series  200  to  600,  with  series  700  and  the  University  forestry  in  the  background. 
Note  the  plot  labels  (shown  in  full  for  series  400),  also  the  oats  harvesting  in  progress  on  series  500. 
None  means  no  soil  treatment  (except  the  regular  crop  system);  Le  means  grain  farming  with  legumes  (including  catch  crops) 
and  crop  residues  returned  to  the  land;  M  means  farm  manure;  L  means  limestone;  /'means  phosphorus;  A'  means  potassium  (kalium) 
>and  A^  means  commercial  nitrogen;  $x  means  five  times  the  standard  applications. 

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THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


329 


330  BULLETIN  No.  125.  [May, 

The  Illinois  Agricultural  Experiment  Station  was  established 
in  1888  and  in  the  reports  made  by  Professor  Morrow  and  his  as- 
sistants relating  to  these  experiments  and  published  in  Experiment 
Station  bulletins  from  1888  to  1894  there  is  no  record  of  crop  yields 
previous  to  1888.  Whether  it  was  considered  sufficient  during  the 
first  nine  years  to  maintain  the  crop  systems  and  wait  for  marked 
differences  to  develop  before  beginning  to  take  exact  crop  yields, 
or  whether  the  funds  provided  were  inadequate  to  meet  the  ex- 
pense of  securing  these  complete  records,  is  not  stated.  Certainly 
the  most  important  thing  is  the  record  that  the  crop  systems  were 
maintained  during  those  early  years. 

Since  1888  these  crop  systems  for  the  three  plots  mentioned 
have  been  essentially  maintained,  with  the  modification  on  Plot 
No.  5  during  the  later  years  of  adopting  the  more  simple  rotation 
of  corn,  oats,  and  clover,  one  year  each.  From  the  recorded  state- 
ments and  the  existing  knowledge  it  is  safe  to  say  that  all  crops 
have  been  removed,  including  the  grain,  hay,  straw,  and  corn  fod- 
der, from  1879  to  the  present  time. 

Originally  these  plots  were  one-half  acre  each  in  size,  being 
5  rods  wide  (north  and  south)  by  16  rods  long  (east  and  west), 
but  in  1904,  because  of  the  enlargement  of  the  University  campus, 
it  became  necessary  to  reduce  the  length  to  9  rods,  in  the  central 
part  of  the  original  plots.  At  the  same  time  one-half  rod  division 
strips  were  established  between  the  plots,  also  a  one-fourth  rod  cul- 
tivated or  cropped  protecting  border  around  the  plotted  area,  and 
each  of  the  three  plots  was  also  divided  in  four  quarters  by  half- 
rod  division  strips  through  the  center  in  both  directions.  Thus 
from  each  of  the  original  plots  we  have  four  plots  of  one-twentieth 
acre  each.  In  each  case  the  two  plots  on  the  north  are  continued 
as  a  duplicate  test  of  the  original  system,  without  the  use  of  manure 
or  commercial  fertilizers,  while  the  two  plots  on  the  south  are 
cropped  the  same,  but  they  are  now  being  improved  by  such  ap- 
plications of  farm  manure  as  can  easily  be  made  from  the  crops 
grown,  by  the  use  of  legume  catch  crops,  applications  of  ground 
limestone  to  correct  possible  soil  acidity,  and  by  the  use  of  phos- 
phorus, applied  for  each  year  in  the  rotation  in  200  pounds  of 
steamed  bone  meal  or  in  600  pounds  of  rock  phosphate  per  acre. 

The  original  plot  numbers  are  retained,  the  untreated  north 
part  being  known  as  3N,  4N,  and  5N ;  and  the  treated  south  part 
as  38,  48,  and  58,  respectively;  and  to  each  of  these  may  be  added 
W  or  E  to  designate  the  west  or  east  half.  Thus  plots  3NW  and 
3NE  are  the  untreated  duplicate  plots  on  which  the  thirtieth  crop 
of  continuous  corn  is  to  be  grown  in  1908;  and,  while  plots  3SW 


I90S.] 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


331 


and  3SE  are  treated  as  above  described,  they,  too,  are  still  kept  in 
corn  every  year.  Corresponding  to  these  are  the  divisions  of  the 
corn  and  oats  plot  (No.  4)  and  of  the  corn-oats-clover  plot 
(No.  5),  which  are  continually  cropped  by  the  respective  rotations, 
the  duplicate  plots  in  the  north  half  receiving-  no  further  treatment, 
while  the  south  half  is  manured  and  fertilized. 

In  Table  2  are  recorded  the  yields  of  these  old  plots  for  the 
last  twenty  years,  from  1888  to  1907,  including  since  1904,  for 
each  rotation  system,  the  average  of  the  untreated  duplicates  and  of 
the  treated  parts. 

TABLE  2.— CROP  YIELDS  PER  ACRE  PROM  THE  OLDEST  PERMANENT  EXPERI- 
MENT PLOTS:  URBANA  SOIL  EXPERIMENT  FIELD 


Years. 

Soil  treatment 
applied. 

Plot  No.  3 

Plot  No.  4. 

Plot  No.  5. 

Corn 
every 
year. 

Two-year 
rotation. 

Three-year 
rotation. 

Corn 
bu. 

Corn 
bu. 

Oats 
bu. 

Corn 
bu. 

Oats 
bu. 

Clover 
tons. 

1879-87 
1888 
1889 
1890 
1891 
1892 
1893 
1894 

None  

None  

54.3 
43.2 
48.7 
28.6 
33.1 
21.7 
34.8 

49.5 

54.3 
33.2 

29.6 

37.4 

37.2 

57.2 

67.6 
34.1 

48.6 
65.1 

4.04 
1.51 
1.46 

None  

None  

None  

None  

None  

None  

1895 
1896 
1897 
1898 
1899 
1900 

None  

42.2 
62.3 
40.1 
18.1 
50.1 
48.0 

41.6 
47.0 
44.4 

34.5 
41.5 

53.5 

22.2 

None  

None  

None  

None  

None  

1901 
1902 
1903 

None  

23.7 
60.2 
26.0 

33.7 
35.9 

56.3 

34.3 

54.6 

1.11 

None  

None  

1904 
1904 

N.  %  None  

21.5 
17.1 

17.5 

25.3 

55.3 

72.7 

a  i/  j  Legume,*Mannre,**  \ 
/2  \  Lime,  Phosphorus**  J 

1905 
1905 

N.^  None  

24.8 
31.4 

50.0 
44.9 

42.3 
50.6 

c  i/  (  Legume,  Manure,  ) 
2  (  Lime,  Phosphorus  f 

1906 
1906 

N.K  None     .    

27.1 
35.8 

34.7 

52.5 

1.43f 
1.74f 

g  y  j  Legume,  Manure,    } 
'/2  \  Lime,  Phosphorus  \ 

1907 
1907 

N.J£  None  

29.0 

48.7 

47.8 
87.6 

80.5 
93.6 

g  y  j  Legume,  Manure,    ) 
2  |  Lime,  Phosphorus    \ 

*L,egume  catch  crops  first  grown  in  1904  to  benefit  1905  crops. 
**Manure  and  phosphorus  first  applied  to  plot  5S  for  1904  crop,  but  to 
plots  3S  and  4S  for  1905  crop.     fCowpea  hay;  the  clover  failed. 


332 


BULLETIN  No.  125. 


[May, 


PLATE  3. — THE  2QTH  CROP  OF  CONTINUOUS  CORN  WITH  NO  MANURE  OR  FERTILIZ- 
ERS: PLOT  3  (UNTREATED  HALF),  URBANA  SOIL  EXPERIMENT  FIELD,  1907: 
YIELD  29.0  BUSHELS  PER  ACRE. 

These  old  plots  lie  west  of  Mathews  avenue  and  immediately 
south  of  the  astronomical  observatory,  which  is  near  the  Agricul- 
tural Building.  These  plots,  as  well  as  the  newer  series  of  plots 
described  more  fully  in  the  following  pages,  were  all  tile-drained 
in  1904,  every  plot  having  a  4-inch  tile  on  one  side,  laid  in  the  half- 
rod  division  strip. 

Seasonal  influences  are  so  great  that  no  very  satisfactory  com- 
parison can  be  made  between  different  years  for  the  sake  of  de- 
termining the  effect  of  the  different  systems  upon  the  productive 
power  of  the  soil,  and  the  thorough  under  drainage  provided  for  in 
1904  must  be  expected  to  markedly  increase  the  crop  yields  in  sub- 
sequent seasons  of  excessive  rainfall,  such  as  1907,  for  example,  as 
compared  with  previous  years.  Thus,  on  the  continuous  corn  plot 
the  yield  was  18.1  bushels  in  1898  and  60.2  bushels  four  years  later, 
in  1902,  and  the  largest  recorded  corn  yield  in  the  corn-oats-clover 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


333 


PLATE  4. — THE  2QTH  CROP  IN  CORN,  OATS,  AND  CLOVER  ROTATION:  PLOT  5 
(TREATED  HALF),  URBANA  SOIL  EXPERIMENT  FIELD,  1907:  YIELD  93.6  BUSH- 
ELS PER  ACRE. 

rotation  was  80.5  bushels  in  the  wet  season  of  1907,  the  land  hav- 
ing been  well  tile-drained  in  1904. 

A  fair  comparison  between  different  systems  can  usually  be 
made  in  the  same  years,  and  the  change  in  productive  power  under 
any  system  can  best  be  ascertained  by  comparing  the  results  from 
the  older  experiments  with  those  from  the  newer  experiments,  as 
shown  in  Table  i,  when  the  effect  of  sixteen  years'  cropping  can  be 
noted.  It  will  be  seen  from  the  following  tabular  statements  that 
every  plot  in  the  newer  experiments  produced  more  than  75  bushels 
of  corn  per  acre  in  1896  and  that  the  average  in  1897  was  about 
70  bushels.  Upon  these  facts  is  based  the  assumption  that  all  of 
the  older  plots  originally  produced  70  bushels  or  more  per  acre. 

It  is  apparent  that  the  legume  catch  crops  (chiefly  cowpeas) 
seeded  in  the  corn  decrease  the  yield  for  the  first  year  at  least,  as 


334  BULLETIN  No.  125.  [May, 

shown  in  1904  on  plot  3  and,  even  in  spite  of  the  light  manuring, 
on  plot  4  in  1905. 

The  general  effect  of  the  system  of  soil  improvement  adopted 
for  the  south  half  of  each  of  these  old  plots  is  already  very  marked, 
an  increase  of  40  bushels  of  corn  per  acre  being  secured  in  1907  from 
the  treatment  on  plot  4,  where  the  most  marked  effect  is  to  be  ex- 
pected because  no  clover  or  other  legumes  had  been  grown  previous 
to  1904  in  this  rotation  and  the  frequent  change  from  corn  to  oats 
has  helped  to  avoid  the  development  of  corn  insects. 

For  the  separate  effect  of  each  individual  kind  of  treatment,  as 
manure,  lime,  or  phosphorus,  reference  must  be  made  to  the  de- 
tailed statements  in  the  tables  of  data  from  the  newer  experiments 
reported  in  the  following  pages. 

THE  NEWER  SERIES  OF  SOIL  EXPERIMENTS 

On  the  opposite  side  of  Mathews  avenue  and  extending  east- 
ward to  the  University  forestry  plantation  are  seven  series  of 
additional  experiment  fields,  laid  out  in  1895  and  brought  under 
definite  systems  of  crop  rotation  and  soil  treatment  since  1900. 

During  at  least  16  years  previous  to  1895  this  land  was  all  in 
pasture  continuously,  and  it  may  perhaps  be  fair  to  assume  that 
the  fertility  of  the  soil  was  essentially  maintained*  during  that 
period,  so  that  16  years  of  crops  harvested  and  removed  may  rep- 
resent the  difference  between  the  old  and  new  fields. 

On  the  new  field,  series  100  lies  immediately  east  of  Mathews 
avenue,  with  series  200  next  east,  and  so  on  to  series  700,  which 
is  near  the  forestry.  Each  series  is  divided  into  10  plots  numbered 
from  north  to  south  from  i  to  10.  Thus,  series  100  contains  plots 
101  to  no;  series  200  contains  plots  201  to  210,  etc.,  etc.  The 
individual  plots  are  2  by  8  rods,  containing  exactly  one-tenth  acre 
each,  aside  from  the  cultivated,  or  cropped,  protecting  border  about 
one-fourth  rod  wide  which  completely  surrounds  every  individual 
plot.  A  higher  degree  of  accuracy  is  made  possible  by  having  an 
outside  row  of  corn  or  strip  of  other  crops  surrounding  each  plot, 
thus  giving  half-rodt  division  strips  between  the  tenth-acre  plots, 
to  prevent  treatment  applied  to  one  plot  from  influencing  the  crop 
yields  on  adjoining  plots. 

Three  series,  100,  200,  and  300,  are  being  cropped  in  the  three- 
year  rotation,  corn,  oats,  and  clover,  in  which  every  crop  may  be 

*If  the  stock  remain  in  the  pasture  day  and  night  and  receive  a  small 
amount  of  grain,  the  fertility  will  be  maintained,  and  with  heavier  feeding  of 
grain  the  fertility  will  be  gradually  increased ;  but  if  the  stock  remain  in  the 
pasture  only  during  the  day  and  receive  no  feed  during  the  night,  the  fertility 
of  the  land  will  be  gradually  reduced,  especially  in  phosphorus.  Abundance  of 
white  clover  in  blue  grass  pastures  will  help  to  maintain  the  nitrogen. 

fThese  strips  are  exactly  8%  meet  in  the  old  field  but  only  7^/3  feet  in  the 
newer  field. 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS.  335 

represented  every  year.  The  next  two  series,  400  and  500,  alter- 
nate in  the  two-year  rotation  of  corn  and  oats.  On  the  two  re- 
maining series,  600  and  700,  corn  is  grown  every  year  in  what  is 
termed  a  complete  fertility  test,  containing  duplicate  plots  treated 
with  commercial  nitrogen,  phosphorus,  and  potassium,  these  ele- 
ments being  applied  singly  and  also  in  every  possible  combination 
in  uniform  amount  and  form,  and  in  addition  a  duplicate  test  is 
made  to  determine  the  effect  of  lime,  and  another  for  "extra  heavy" 
treatment. 

On  the  three  series  of  plots  in  the  three-year  rotation,  100,  200, 
and  300,  and  on  the  two  series  of  plots  in  the  two-year  rotation, 
400  and  500,  no  commercial  nitrogen  is  applied,  but  the  investiga- 
tion is  designed  to  furnish  information  concerning  the  value  of 
farm  manure  and  legume  crops  and  other  crop  residues  in  practical 
systems  of  live  stock  farming  and  of  grain  farming.  These  sys- 
tems are  each  practiced  without  additional  treatment,  and  also  with 
the  addition  of  lime,  of  lime  and  phosphorus,  and  of  lime,  phos- 
phorus, and  potassium.  There  is  also  in  each  of  the  five  series  one 
plot  (No.  i)  that  receives  no  treatment  (aside  from  the  crop  rota- 
tion) and  another  plot  (No.  10)  that  receives  "extra  heavy"  treat- 
ment by  which  it  is  hoped  to  remove  the  soil  limit  in  crop  produc- 
tion. In  other  words,  the  treatment  of  plot  10  is  designed  to  show 
how  large  crops  can  be  grown  in  Illinois  with  the  rainfall  and  sun- 
shine as  the  only  limiting  factors,  all  controllable  factors  being  pro- 
vided for,  even  at  heavy  expense. 

Following  is  the  general  plan  of  soil  treatment  for  the  ten  plots 
in  each  of  the  five  series,  100  to  500. 

PLAN  OF  SOIL  TREATMENT:    SERIES  100  TO  500 


Plot  No. 


Soil  treatment. 


9. 
10. 


None 

L/egume  (catch  crops  and  crop  residues) 

Manure 

L<egume,  lime 

Manure,  lime 

I^egume,  lime,  phosphorus 

Manure,  lime,  phosphorus 

Ivegume,  lime,  phosphorus,  potassium 

Manure,  lime,  phosphorus,  potassium 

I^egume,  manure  x  5,  lime,  phosphorus  x  5 


The  lime  was  applied  at  the  rate  per  acre  of  250  pounds  of  air- 
slacked  in  1902  and  600  pounds  of  limestone  in  1903. 


336  BULLETIN  No.  125.  [May, 

The  phosphorus  has  been  applied  at  the  rate  per  annum  of 
25  pounds  of  the  element  in  200  pounds  of  steamed  bone  meal  since 
1902,  the  present  practice  being  to  apply  600  pounds  of  bone  meal  to 
the  clover  land  to  be  plowed  under  for  corn.  Beginning  with  1908 
the  west  half  of  all  plots  receiving  phosphorus  will  be  treated  with 
rock  phosphate,  while  the  use  of  bone  meal  will  be  continued  on 
the  east  half.  The  potassium  has  been  applied  at  the  yearly  rate  of 
42  pounds  per  acre  in  100  pounds  of  potassium  sulfate,  usually  in 
connection  with  the  bone  meal,  the  steamed  bone  being  run  through 
the  grain  box  and  the  potassium  salt  through  the  fertilizer  box  of 
an  ordinary  fertilizer  drill. 

The  six  series,  100  to  600,  were  laid  out  in  the  spring  of  1895 
by  Dean  Eugene  Davenport,  who  came  to  the  University  in  January 
of  that  year.  It  was  necessary  to  break  the  old  pasture  sod  in  the 
spring,  and,  as  might  be  expected,  the  corn  crop  for  that  year  was 
poor.  Series  700  was  broken  later  in  1895  and  all  plots  were 
cropped  in  corn  in  1896  and  1897,  in  order  that  any  marked  differ- 
ences in  the  soil  might  be  noted. 

From  1897  to  1900,  Professor  P.  G.  Holden  was  in  charge  of 
the  work  reported  in  this  bulletin.  Series  100  to  300  were  cropped 
somewhat  irregularly,  oats,  cowpeas,  and  clover  being  the  principal 
crops  grown,  with  some  catch  crops  one  year  on  certain  plots,  as 
shown  in  the  following  tables,  and  series  400  to  700  were  cropped 
in  corn  every  year. 

The  definite  crop  rotations  were  begun  in  1901  and  the  appli- 
cations of  lime,  phosphorus,  and  potassium  have  been  made  as 
stated  above  and  as  shown  in  the  tables.  The  growing  of  legume 
catch  crops  was  begun  in  1901  for  the  benefit  of  the  succeeding 
crops,  and  a  comparison  of  plots  2,  4,  6,  and  8  with  plots  3,  5,  7, 
and  9  will  show  what  effect  was  produced  by  these  catch  crops  dur- 
ing the  three  years,  1902,  1903,  and  1904. 

Beginning  with  1905,  manure  has  been  applied  as  indicated  in 
the  tables,  which  will  afford,  when  the  results  for  1908  and  1909 
become  available,  a  comparison  between  manure  and  legume  catch 
crops  for  three  years  on  each  series.  The  standard  applications  of 
manure  are  the  same  weights  of  average  fresh  farm  manure  (con- 
taining about  25  percent  of  dry  matter)  as  the  weights  of  air-dry 
produce  secured  from  the  same  plots  during  the  previous  rotation. 
This  allows  about  one-third  of  the  produce  to  be  sold  and  also  al- 
lows a  loss  of  20  percent  of  the  manure  possible  to  be  produced 
from  the  remaining  two-thirds.  On  plot  10  about  five  times  as 
much  manure  and  phosphorus  are  applied  as  on  the  other  plots,  but 
this  "extra  heavy"  treatment  was  begun  in  1906,  only  lime,  phos- 
phorus, and  potassium  having  been  applied  in  previous  years. 


1908.] 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


337 


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THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


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340 


BULLETIN  No.  125. 


PLATE  5. — CORN  AFTER  CLOVER  WITH  NO  SPECIAL  SOIL  TREATMENT:     PLOT  301, 
URBANA  SOIL  EXPERIMENT  FIELD,  1907:    YIELD  80.5  BUSHELS  PER  ACRE. 

The  complete  grain  system  is  first  put  under  way  for  the  1908 
corn  crop,  the  equivalent  of  the  clover  grown  in  1907  having  been 
returned  to  the  legume  plots  (102,  104,  106,  and  108)  to  be  plowed 
under  for  corn.  The  corn  stalks  will  be  disked  down  when  seeding 
to  oats  and  clover  in  the  spring,  and  the  effect  of  this  on  a  subse- 
quent crop  of  corn  on  series  300  cannot  be  seen  till  1913.  Thus, 
while  much  valuable  information  has  already  been  secured  from 
these  fields,  as  shown  in  this  bulletin  and  in  Circular  96  (published 
in  1905),  it  should  be  kept  in  mind  that  the  full  effect  of  these  sys- 
tems of  soil  improvement  will  not  be  seen  for  several  years. 

THREE- YEAR  ROTATION 

In  Tables  3,  4,  and  5  are  reported  in  detail  the  crop  yields  from 
series  100,  200,  and  300,  for  the  13  years  from  1895  to  1907. 


1908.] 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


341 


PLATE  6. — CORN  AFTER  CLOVER  WITH  LEGUME-LIME-PHOSPHORUS  TREATMENT 
(GRAIN  FARMING)  :  PLOT  306,  URBANA  SOIL  EXPERIMENT  FIELD,  1907 : 
YIELD  104.6  BUSHELS  PER  ACRE. 

With  few  exceptions  all  yields  of  grain  and  hay  are  recorded 
in  the  tables,  and  a  financial  statement  is  also  given  at  the  bottom 
of  each  table  showing  the  effect  of  each  addition  in  the  soil  treat- 
ment during  the  last  three  years,  on  each  series  of  plots,  counting 
corn  at  35  cents  a  bushel,  oats  at  25  cents,  and  hay  at  $6  a  ton. 

It  will  be  seen  that  but  little  effect  has  been  produced  by  sowing 
legume  catch  crops  in  the  corn  in  the  three-year  rotation,  where 
corn  is  followed  by  oats  and  clover.  From  1902  to  1905-6-7,  the 
legume  catch  crops  produced  but  little  benefit  on  other  crops,  as 
shown  by  comparing  plots  2,  4,  6,  and  8  with  plots  3,  5,  7,  and  9, 
except  on  the  oat  crop  in  1904  and  1905. 

The  effect  of  the  farm  manure  on  each  of  the  three  crops  is 
shown  only  in  Table  3  (series  100),  the  manure  on  series  200  and 
300'  having  benefited  only  two  crops  and  one  crop,  respectively.  Six 
tons  of  manure  per  acre  on  series  100  have  produced  increases  in 


342  BULLETIN  No.  125.  [May, 

the  three  crops  amounting  to  $9.60  per  acre,  or  to  $1.60  per  ton 
of  manure  applied,  leaving  a  profit  of  $1.30  a  ton  for  the  manure 
of  the  farm  if  it  can  be  hauled  and  spread  for  30  cents  a  ton.  Of 
still  greater  interest  will  be  the  effect  on  the  next  three  crops  of  the 
second  application  of  manure;  (made  for  the  1908  corn  crop  on 
series  100),  including  any  possible  residual  effect  carried  over  from 
the  previous  application. 

Aside  from  the  legume  and  manure,  there  is  a  duplicate  test 
for  each  addition,  and  the  effect  is  determined  independent  of  the 
check  plot  (No.  i).  Thus  the  effect  of  lime  is  determined  by  com- 
paring plots  4  and  5,  not  with  plot  I,  but  with  plots  2  and  3;  and 
the  effect  of  phosphorus  is  determined  by  comparing  plots  6  and  7 
with  plots  4  and  5,  respectively. 

On  five  plots  out  of  six  lime  has  shown  some  increase,  and  on 
three  plots  it  has  paid  more  than  50  cents  per  acre  per  annum, 
which  is  more  than  sufficient  to  pay  for  the  applications  actually 
made  to  these  plots,  but  the  results  vary  so  greatly  with  the  differ- 
ent crops  and  seasons  that  safe  conclusions  cannot  be  drawn  until 
further  data  are  secured.  The  apparently  marked  effects  on  plots 
304  and  305  are  evidently  due  in  part  at  least  to  original  soil  dif- 
ferences,* indicated  in  the  early  records  for  those  plots,  as  compared 
with  302  and  303. 

Aside  from  farm  manure  the  only  well  established  benefit  is 
derived  from  the  application  of  phosphorus,  which  has  produced  a 
marked  increase  on  every  plot  and  in  five  cases  out  of  six  has  much 

*The  large  amount  of  data  accumulated  and  reported  in  the  preceding  and 
following  pages  concerning  these  plots  previous  to  the  beginning  of  soil  treat- 
ment has  suggested,  of  course,  that  even  small  natural  soil  differences  could  be 
detected  in  the  early  yields  secured  under  similar  conditions  of  cropping,  so  that 
corrections  might  be  made  for  such  natural  variations  when  considering  subse- 
quent yields  as  affected  by  soil  treatment  A  careful  study  of  all  the  results 
shows,  however,  that  it  is  very  unsafe  to  try  to  make  any  such  corrections.  That 
plot  A  has  produced  larger  yields  than  plot  B  for  two  or  three  years  does  not 
prove  that  it  will  continue  to  do  so.  In  fact,  under  normal  conditions,  this  relation 
may  be  reversed.  The  larger  crops  from  plot  A  remove  more  plant  food,  and 
the  later  crops  may  be  smaller  in  consequence ;  whereas,  if  smaller  crops  are 
removed  from  plot  B  in  the  early  years,  the  yields  may  be  larger  than  on  plot 
A  in  subsequent  years. 

Several  illustrations  of  this  have  actually  occurred  in  these  experiments. 
Thus  for  the  three  years,  1895  to  1897,  plot  406  produced,  as  an  average,  5  bush- 
els more  corn  per  acre  than  plot  506,  but  as  an  average  of  the  next  three  years 
plot  506  produced  2.9  bushels  more  corn  per  acre  than  plot  406.  Likewise,  a 
decision  based  upon  the  first  three  years  would  hold  the  natural  productiveness 
of  plot  407  to  be  3.8  bushels  higher  than  plot  507,  but  the  records  of  the  next 
three  years  would  reverse  the  decision  because  for  those  years  plot  407  was  not 
3.8  bushels  better  but  3.1  bushels  poorer  than  plot  507,  as  an  average.  The  aver- 
age yield  for  the  entire  six  years  differs  by  less  than  half  a  bushel  for  these 
two  plots.  (See  also  the  last  page  of  this  bulletin.) 

Because  of  these  facts  it  seems  unsafe  to  try  to  make  any  corrections  or 
to  use  "corrected"  results.  The  data  actually  secured  are  correctly  reported 
and  if  there  is  reason  to  believe  that  any  results  are  untrustworthy  they  may  be 
discarded. 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS.  343 

more  than  paid  for  its  cost  even  in  200  pounds  per  annum  of 
steamed  bone  meal,  in  which  more  phosphorus  is  applied  than  is 
removed  from  the  soil  in  the  crops  grown.  This,  of  course,  gives 
promise  of  some  residual  effect  in  subsequent  years,  more  especially 
for  clover,  because  the  land  is  growing  richer  year  by  year  in  phos- 
phorus and  because  clover  should  not  be  limited  in  yield  by  lack  of 
nitrogen,  while  corn  or  oats  may  be,  no  matter  how  much  phos- 
phorus is  supplied. 

The  very  marked  effect  of  phosphorus  upon  the  yield  of  clover 
during  the  last  three  years,  averaging  more  than  75  percent  in- 
crease, is  especially  significant,  and  constitutes  probably  the  most 
valuable  information  furnished  from  these  particular  experiment 
fields. 

The  addition  of  potassium  has  produced .  some  increase  on  most 
plots,  but  never  sufficient  to  pay  for  even  one-half  its 'cost.  The 
effect  of  potassium  indicates  the  need  of  more  decaying  organic 
matter,  which  has  power  to  liberate  sufficient  potassium  from  the 
immense  total  supply  in  the  soil.  (Soil  samples  59  to  421,  whose 
analyses  are  reported  on  page  270  of  Bulletin  123  were  collected  in 
1901  from  series  100  to  700,  respectively,  and  samples  467  to  472 
from  plot  3  of  the  old  experiment  field.) 

TWO-YEAR  ROTATION 

In  Tables  6  and  7  are  given  data  from  the  two-year  rotation  of 
corn  and  oats  on  series  400  and  500. 

It  will  be  seen  that  corn  was  grown  for  six  years  on  series  400 
and  500  before  the  two-year  rotation  was  begun.  The  subsequent 
substitution  of  oats  for  corn  in  alternate  years  lessens  the  liability  to 
insect  injury  and  somewhat  reduces  the  draft  upon  the  soil,  so  that 
larger  corn  yields  are  likely  to  be  secured  for  a  few  years  than 
were  produced  near  the  close  of  the  six  years  of  continuous  corn, 
even  with  no  increase  in  the  annually  available  fertility. 

The  legume  catch  crops,  as  cowpeas  seeded  in  the  corn  at  the 
last  cultivation  or  clover  seeded  with  the  oats,  have  produced  but 
little  effect,  and  this  effect  has  been  a  decrease  as  often  as  an  in- 
crease in  the  regular  crops.  Plot  i  is  apparently  slightly  better  land 
than  plots  2  and  3,  as  indicated  by  the  crop  yields  secured  previous 
to  the  beginning  of  soil  treatment;  but  a  comparison  of  plots  2, 
4,  6,  and  8  with  plots  3,  5,  7,  and  9,  from  1902  to  1904-5  shows 
only  a  small  average  benefit  on  the  oats.  On  the  other  hand,  the 
legume  treatment  produced  noticeably  larger  yields  of  corn  in  1907 
than  were  obtained  from  the  plots  to  which  light  applications  of 
farm  manure  had  been  applied. 

As  a  rule  lime  has  produced  some  increase,  but  as  an  average 
it  amounts  to  but  little  more  than  cost. 


344 


BULLETIN  No.  125. 


[May, 


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THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


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Cost  for  two  years  

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V 

346  BULLETIN  No.  125.  [May, 

Phosphorus  has  nearly  always  produced  an  appreciable  increase 
on  both  corn  and  oats,  and  as  an  average  of  twenty-two  tests,  cov- 
ering the  six  years,  the  value  of  the  increase  is  greater  than  the 
cost  of  the  phosphorus  in  steamed  bone  meal,  and  the  amount  of 
phosphorus  applied  (25  pounds  per  acre  for  each  year)  is  nearly 
twice  as  much  as  removed  in  the  cropsj  so  that  the  soil  is  being  en- 
riched quite  rapidly  in  phosphorus. 

It  must  be  understood,  however,  that  phosphorus  alone  cannot 
make  the  soil  highly  productive,  because  the  nitrogen  limit  is  but 
little  higher  than  the  limit  due  to  phosphorus,  and  the  yields  cannot 
be  very  high  unless  ample  provision  is  made  for  both  elements. 
The  three-year  rotation  makes  better  provision  for  nitrogen,  and 
in  consquence  the  crop  yields  are  not  only  larger  but  the  phos- 
phorus also  becomes  more  effective. 

Thus,  as  an  average  of  the  last  three  years,  plot  4  (without 
phosphorus)  has  produced  63  bushels  of  corn  per  acre,  in  the  two- 
year  rotation,  and  72  bushels  in  the  three-year  rotation,  while  plot  6 
(with  phosphorus)  has  averaged  72  bushels  per  acre  in  the  two- 
year  rotation,  and  90  bushels  in  the  three-year  rotation.  In  other 
words,  phosphorus  has  made  an  average  increase  of  18  bushels  per 
acre  in  the  three-year  rotation,  but  only  9  bushels  in  the  two-year 
rotation.  Smaller  but  nearly  proportionate  differences  have  been 
made  as  an  average  of  all  tests  with  corn  and  oats  during  the  last 
three  years,  larger  yields  having  been  secured  in  the  three-year  ro- 
tation and  the  difference  between  that  and  the  two-year  rotation 
being  still  greater  where  phosphorus  is  applied  to  both. 

As  an  average  of  all  tests  during  the  past  three  years  the  value 
of  the  crops  on  plots  6  and  7  has  been  about  one  dollar  an  acre  a 
year  greater  for  the  three-year  rotation  than  for  the  two-year  ro- 
tation, counting  corn  at  35  cents  a  bushel,  oats  at  25  cents,  and 
clover  hay  at  $6  a  ton.  At  higher  prices  the  difference  in  favor  of 
the  three-year  rotation  would  be  still  greater.  Furthermore  some 
clover  seed  has  been  secured  in  the  three-year  rotation,  but  we  have 
begun  to  try  to  save  clover  seed  only  recently  and  have  as  yet  too 
little  data  on  that  crop  to  justify  further  discussion  of  it. 

Potassium  has  actually  reduced  the  yield  as  an  average  of  all 
tests  in  the  two-year  rotation  during  the  entire  period  of  six  years, 
the  average  decrease  amounting  to  2  bushels  of  corn  and  4  bushels 
of  oats  per  acre,  aside  from  the  total  loss  of  the  cost  of  the  potas- 
sium applied. 

CONTINUOUS  CORN  IN  COMPLETE  FERTILITY  EXPERIMENTS 

In  Tables  8  and  9  are  reported  the  corn  yields  from  series  600 
and  700,  where  experiments  are  in  progress  which  include  the  use 
of  commercial  nitrogen,  phosphorus,  and  potassium,  singly  and  in 


1908.]  THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS.  347 

all  combinations.  In  all  tests  there  are  duplicate  plots  with  the 
same  kind  of  treatment.  Besides  this  two  plots  remain  untreated 
(601  and  602),  two  are  treated  with  lime  only  (603  and  604),  and 
two  plots  are  now  being  given  "extra  heavy"  treatment,  including 
farm  manure. 

Corn  is  grown  every  year  in  these  complete  fertility  experi- 
ments, a  part  of  the  investigation  being  to  ascertain  how  much  of 
the  rapid  decrease  in  yield  resulting  from  continuous  corn  growing 
is  due  to  insect  injuries  and  how  much  is  due  to  other  causes,  such 
as  depletion  of  decaying  organic  matter  and  lack  of  available  plant 
food.  In  other  words,  the  experiments  on  series  600  and  700  are 
designed,  not  to  demonstrate  any  good  system  of  farming,  but 
rather  to  secure  definite  information  concerning  insect  injuries, 
plant  food  requirements,  and  possible  injurious  effects  of  too  much 
corn-growing  on  the  same  land,  as  contrasted  with  a  good  crop 
rotation  such  as  is  practiced  on  series  100,  200,  and  300. 

Plots  60 1  and  602  serve  as  duplicate  check  plots  on  which  corn 
is  grown  every  year  with  good  preparation  of  the  land  and  with 
good  cultivation  of  the  crop,  but  the  entire  crop  is  harvested  and 
removed,  and  no  manure  or  fertilizer  is  returned.  (See  Table  8). 

On  plots  603  and  604  a  duplicate  test  is  made  to  determine  the 
effect  of  applying  lime,  and  on  the  other  six  plots  in  the  600  series 
are  duplicate  tests  with  each  of  the  three  elements,  nitrogen,  phos- 
phorus, and  potassium,  the  effect  of  each  element  being  determined 
by  comparing  the  results  obtained  with  the  yields  of  plots  603  and 
604. 

On  the  700  series  (Table  9)  a  duplicate  test  is  made  of  every 
possible  pair  of  elements  and  of  all  three  elements  together  (plots 
707  and  708),  and  "extra  heavy"  treatment  is  applied  to  the  last 
two  plots  (709  and  710). 

It  will  be  seen  that  no  treatment  was  applied  to  any  of  the  plots 
previous  to  1901.  From  1901  to  1905  nitrogen  was  applied  at  the 
rate  of  100  pounds  per  acre  a  year.  That  is  less  than  the  nitrogen 
contained  in  a  7O-bushel  crop  of  corn.  It  soon  became  apparent, 
however,  that  that  amount  was  not  sufficient  to  meet  the  nitrogen 
requirements  of  the  crops  actually  grown  and  that  the  crop  yields 
on  certain  nitrogen  plots  were  decreasing  because  of  insufficient 
nitrogen,  consequently,  beginning  with  1906,  the  annual  applica- 
tion was  increased  to  250  pounds  per  acre  of  the  element  nitrogen. 
This  provides  sufficient  nitrogen  for  a  hundred-bushel  crop  of  corn 
and  allows  for  a  loss  in  drainage  water  of  40  percent  of  the  nitro- 
gen applied,  a  loss  which  is  no  greater  than  commonly  occurs  where 
commercial  nitrogen  is  used. 


348 


BULLETIN  No.  125. 


[May, 


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THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


349 


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350 


BULLETIN  No.  125. 


[May, 


In  1901  the  nitrogen  was  applied  in  sodium  nitrate,  but  since 
that  year  dried  blood  has  been  used  as  the  nitrogen  fertilizer.  It 
is  well  to  keep  in  mind  that  while  nitrogen  can  be  secured  with 
profit  from  the  inexhaustible  supply  of  the  air  by  means  of  clover 
and  other  legume  crops,  it  costs  at  least  15  cents  a  pound  in  com- 
mercial form.  The  250  pounds  of  nitrogen  now  being  applied  each 
year  to  all  nitrogen  plots  on  series  600  and  700  costs  at  least  $37.50 
per  acre  a  year. 

It  should  be  understood  that  the  growing  of  clover  produces 
several  effects  on  the  land  and  upon  subsequent  yields  of  other 
crops,  only  one  of  whch  is  due  to  the  nitrogen  secured  from  the 
air.  In  fact  the  chief  effect  of  clover  in  increasing  the  yield  of  a 
subsequent  crop  of  corn  is  not  due  to  the  nitrogen  secured  from 
bie  air,  but  rather  to  the  liberation  of  phosphorus  by  the  decay  of 
the  clover  residues  in  the  soil.  The  physical  improvement  of  the 
soil  and  subsoil  are  also  important  factors  in  some  cases. 


PLATE  7. — CORN  EVERY  YEAR  WITH  NO  MANURE  OR  FERTILIZERS  :     PLOT  602,  UR- 
BANA  SOIL  EXPERIMENT  FIELD,  1907 :     YIELD  34.6  BUSHELS  PER  ACRE. 


1908.] 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 


351 


But  to  determine  the  need  and  the  effect  of  nitrogen  itself  we 
must  apply  nitrogen  in  some  form  and  dried  blood  is  the  most  sat- 
isfactory form  to  use.  Sodium  nitrate  and  ammonium  sulfate  are 
also  common  concentrated  nitrogen  fertilizers  but  they  are  soluble 
salts  which  may  produce  marked  indirect  effects,  not  infrequently 
of  greater  consequence  than  the  effect  due  to  the  nitrogen  itself. 

Phosphorus  has  been  applied  in  steamed  bone  meal  at  the  rate 
of  25  pounds  of  the  element  per  acre  per  annum,  the  requirement 
of  a  hundred-bushel  crop  of  corn  being  23  pounds,  and  the  annual 
loss  in  drainage  water  being  about  i  pound  per  acre.  The  annual 
cost  of  the  bone  meal  is  $2.50  per  acre. 

Potassium  is  applied  at  the  rate  of  42  pounds  per  acre  a  year  in 
100  pounds  of  potassium  sulfate,  also  at  a  cost  of  $2.50.  A  hun- 
dred-bushel crop  of  corn  contains  19  pounds  of  potassium  in  the 
grain  and  52  pounds  in  the  stalks.  The  application  made  is  not 


PLATE  8. — CORN   EVERY   YEAR  WITH   "EXTRA  HEAVY"   SOIL  TREATMENT  :     PLOT 
709,  URBANA  SOIL  EXPERIMENT  FIELD,  1907:    YIELD  71.8  BUSHELS  PER  ACRE. 


352  BULLETIN  No.  125.  [May, 

sufficient  for  the  entire  crop,  but  the  natural  supply  of  potassium  in 
the  soil  is  so  exceedingly  large  that  it  is  both  unnecessary  and  un- 
profitable to  return  the  potassium  removed  from  the  land  in  any 
ordinary  systems  of  farming. 

On  plots  709  and  710,  beginning  in  1906,  the  application  of 
phosphorus  was  increased  to  five  times  the  standard  amount,  and 
the  application  of  manure  was  begun,  using  about  five  times  as 
much  manure  as  could  easily  be  made  from  the  crops  grown,  or 
20  tons  per  acre  each  year.  The  addition  of  commercial  potassium 
was  discontinued  on  both  plots  and  commercial  nitrogen  was  also 
discontinued  on  710,  but  is  still  used  on  plot  709,  at  the  rate  of 
250  pounds  per  acre  each  year  since  1906. 

The  plots  on  series  600  and  700  are  not  quite  so  uniform  in 
character  and  in  natural  productive  power  as  on  series  100  to  500, 
but  since  being  tile-drained  in  1904  the  natural  differences  are  re- 
duced. It  may  be  seen  that  in  1896,  for  example,  plots  703  to  706 
were  among  the  best  yielding  plots,  while  in  the  season  of  1898 
those  four  plots  produced  markedly  smaller  yields  than  the  other 
plots  in  the  series.  This  is  explained  in  the  foot  note  to  Table  9. 

One  other  natural  condition  should  be  understood:  A  slight 
ridge  crosses  series  600  and  700,  the  crest  passing  through  plots 
606  and  607  and  through  708.  The  lowest  plots  in  the  600  series 
are  the  end  plots,  60 1  and  610,  while  in  the  700  series  the  lowest 
parts  are  plot  710  and  the  depression  that  covers  part  of  plots  703, 
704,  705,  and  706.  Because  of  the  continuous  cropping  with  a 
cultivated  crop  these  two  series  are  continuously  exposed  to  sur- 
face washing,  and  there  is  some  tendency  for  surface  wash  to  be 
deposited  on  601,  610,  and  710  and  to  a  less  extent  on  the  four  plots 
affected  by  the  depression  mentioned.  There  is  also  a  slight  ten- 
dency for  the  dried  blood  applied  to  plots  605  and  606  to  be  carried 
north  to  plot  604  and  south  to  607. 

Because  of  these  facts  the  most  trustworthy  data  are  secured 
from  plots  602,  603,  605,  606,  608,  and  609  and  from  plots  701, 
702,  707,  708,  and  709,  and  this  is  recognized  in  making  the  sum- 
mary given  in  the  lower  part  of  Tables  8  and  9. 

EFFECT  OF  LIME. — The  effect  of  lime  on  the  yield  of  corn  is 
chiefly  due  to  the  fact  that  calcium  carbonate  (limestone)  encour- 
ages nitrification  and  the  consequent  liberation  of  the  nitrogen  and 
to  a  less  extent  of  the  phosphorus  contained  in  the  natural  humus 
of  the  soil.  This  is  best  seen  by  comparing  plots  603  and  602. 
The  summary  shows  an  increase  from  lime  of  3.2  bushels  in  1901-2, 
rising  to  4.5  bushels  in  1903-4,  and  falling  to  2.5  bushels  in  1907. 
Plot  604  shows  larger  effects,  but  the  possible  washing  of  dried 
blood  from  the  adjoining  plot  may  account  for  this  difference. 


THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS. 

Plot  709  compared  with  the  average  of  707  and  708  shows  an 
average  increase  of  2  bushels  per  acre  from  lime  from  1901  to  1905. 

From  all  of  the  investigations  thus  far  conducted  on  the  com- 
mon brown  silt  loam  prairie  soils  of  the  Illinois  corn  belt,  it  is 
evident  that  the  time  is  near  for  most  of  this  soil,  and  already  here 
for  some  of  it,  when  ground  limestone  must  be  applied  to  give  the 
most  profitable  results  in  crop  yields.  These  soils  were  not  rich  in 
lime  in  the  beginning,  and  lime  is  constantly  being  lost  from  the 
soil,  both  in  crops  removed  and  in  the  drainage  waters,  which  per- 
colate through  the  soils  and  when  collected  in  surface  wells  are  al- 
ways recognized  as  "hard"  waters  because  of  the  lime  contained 
in  them. 

EFFECT  OF  NITROGEN  AND  PHOSPHORUS. — The  effect  of  nitro- 
gen is  determined*  by  comparing  plots  605  and  606  with  plot  603. 
These  results  are  summarized  in  the  lower  part  of  Table  8.  They 
show  but  very  little  effect  from  nitrogen  in  1901-2,  the  average  in- 
crease being  about  il/2  bushels.  This  was  raised  to  about  5^  bush- 
els in  1903-4  to  13  bushels  in  1905-6  and  to  16  bushels  in  1907.  It 
is  noteworthy,  however,  that  this  increasing  difference  is  not  due 
to  an  actual  increase  in  yield  on  the  nitrogen  plots,  but  rather  to  a 
decrease  in  the  yield  of  the  plots  not  receiving  nitrogen,  so  far  as 
we  can  judge. 

By  comparing  plots  608  and  603  we  have  the  most  trustworthy 
data  as  to  the  effect  of  phosphorus  with  no  addition  of  nitrogen  or 
potassium.  This  shows  an  average  increase  of  5.4  bushels  during 
the  four  years,  1901  to  1904,  chiefly  produced  during  the  second 
and  third  years.  The  gain  was  3.5  bushels  for  1905-6;  while  the 
effect  in  1907  was  a  loss  of  5.1  bushels.  The  somewhat  higher 
yields  on  plot  607  may  be  due  to  dried  blood  washed  over  from  606. 

In  comparison  with  nitrogen,  it  will  be  seen  that  at  the  begin- 
ning of  soil  treatment  in  1901  phosphorus  was  clearly  the  limiting 
element  and  produced  a  greater  effect  than  nitrogen  during  the  first 
four  years,  after  which  the  effect  of  phosphorus  soon  decreased  un- 
til it  produced  smaller  yields  than  the  untreated  plots,  while  the  ef- 
fect of  nitrogen  has  been  nearly  to  maintain  the  actual  crop  yields, 
with  increasing  differences  above  the  untreated  land. 

The  lesson  taught  by  these  experiments  is  that  on  our  ordinary 
corn  belt  prairie  soils  phosphorus  is  the  most  deficient  element  of 
plant  food,  because  of  which  nitrogen  applied  alone  produces  little 
or  no  increase  in  crops ;  but  in  continuous  corn  growing  the  supply 
of  nitrogen  is  so  rapidly  depleted  by  removal  in  crops  and  in  drain- 
age waters  that  within  a  few  years  nitrogen  itself  becomes  the  most 

*Plot  605  is  probably  the  more  trustworthy  of  the  two  nitrogen  plots  be- 
cause of  possible  wash  from  607  to  a  part  of  606. 


354  BULLETIN  No.  125.  [May, 

deficient  element,  after  which  phosphorus  alone  has  no  power  to 
increase  the  crop  yields. 

Thus  on  plots  605  and  606,  more  than  60  bushels  were  grown 
in  1900,  and,  although  nitrogen  has  been  applied  every  year  since, 
that  yield  has  not  been  equaled;  whereas  on  plots  607  and  608 
phosphorus  actually  increased  the  yields  for  two  or  three  years.* 
After  that  time  the  yields  have  been  nearly  maintained  on  the  nitro- 
gen plots  but  have  steadily  decreased  on  the  phosphorus  plots,  ni- 
trogen having  become  the  limiting  element. 

If,  now,  we  first  restore  the  nitrogen  so  as  to  remove  the  nitro- 
gen limit  to  crop  yields,  then  phosphorus  should  again  have  power 
to  increase  the  yield  above  that  produced  by  nitrogen  on  plots  605 
and  606,  which  averaged  53  bushels  for  1906  and  1907.  This  has 
been  done  on  plots  701  and  702,  where  both  nitrogen  and  phos- 
phorus have  been  applied  and  where  the  average  yield  for  1906  and 
1907  has  been  69  bushels  per  acre.  This  is  16  bushels  higher  than 
on  the  nitrogen  plots  (605  and  606)  and  30  bushels  higher  than 
on  the  phosphorus  plot  (608). 

This  is  shown  in  greater  detail  in  the  summary  in  the  lower 
part  of  Table  9.  The  effect  of  nitrogen  and  phosphorus  above  that 
of  phosphorus  alone  was  3.3  bushels  in>  1901-2,  16.5  bushels  in 
1903-4,  25.4  bushels  in  1905-6,  and  31.9  bushels  in  1907;  where- 
as, the  effect  of  phosphorus  applied  in  addition  to  nitrogen  was  7.  i 
bushels  the  first  two  years,  about  16  bushels  the  next  four  years, 
but  only  10.8  bushels  in  1907.  Here  again  the  apparent  gain  for 
nitrogen  is  not  due  to  increasing  yields  on  plots  701  and  702,  which 
as  a  matter  of  fact  were  about  the  same  in  1904-5  as  they  were  in 
1906-7,  but  the  difference  is  due  rather  to  the  actual  decrease  on 
the  phosphorus  plot  (608)  where  nitrogen  has  become  the  limit- 
ing element. 

It  is  very  apparent  that  nitrogen  alone  cannot  increase  the  yield 
of  corn  on  this  soil,  and  that  the  increase  from  phosphorus  alone 
is  very  temporary,  but  that  both  nitrogen  and  phosphorus  together 
have  power  to  produce  a  decided  increase.  This  is  in  harmony 
with  the  marked  benefit  of  phosphorus  on  clover,  which  has  power 
to  secure  nitrogen  from  the  air  when  the  soil  nitrogen  becomes  de- 
ficient, as  shown  in  the  three-year  rotation  (Tables  3,  4,  and  5). 

EFFECT  OF  POTASSIUM. — The  effect  of  potassium  can  be  ascer- 
tained by  comparing  plot  609  with  plot  603,  also  by  comparing  707 
and  708  with  the  average  of  701  and  702.  Under  the  most  favor- 
able conditions,  with  both  nitrogen  and  phosphorus  present,  the 
addition  of  potassium  produced  an  average  increase  of  3  bushels  in 

*The  year  1901  must  be  overlooked  because  of  the  drouth. 


/90<S.]  THIRTY  YEARS  OF  CROP  ROTATIONS  IN  ILLINOIS.  355 

1901-2,  but  this  has  steadily  grown  less  and  amounted  to  nothing 
in  1907. 

FURTHER  OBSERVATIONS. — Tables  8  and  9  afford  other  inter- 
esting comparisons  and  valuable  information.  For  example,  plot 
602  produced  86.5  bushels  and  plot  709  produced  5.6.2  bushels  of 
corn  per  acre  in  1896,  but  in  1906  (ten  years  later)  plot  602  (un- 
treated) produced  only  30.8  bushels,  while  plot  709  (treated)  pro- 
duced 92.9  bushels  per  acre.  In  other  words,  the  yield  of  plot  709 
was  increased  by  16  bushels  while  the  yield  of  plot  602  decreased 
by  55  bushels  per  acre  in  eleven  years. 

With  liberal  supplies  of  available  plant  food  large  crops  have 
been  grown  with  corn  every  year  in  spite  of  insect  injuries,  which 
have  been  very  noticeable  on  the  continuous  corn  plots,  especially 
the  injuries  from  the  corn  root  worm  which  cause  the  corn  to  fall 
or  to  be  blown  over  easily  on  all  continuous  corn  plots,  while  the 
corn  on  the  rotated  plots  stands  up  well. 

An  interesting  and  suggestive  relationship  appears  between  the 
comparable  plots  in  the  600  and  700  series.  Plots  2,  7,  8,  and  9 
in  the  two  series  lie  end-to-end  and  for  reasons  previously  explained 
they  are  considered  trustworthy  and  comparable  plots. 

Corn  was  grown  on  the  600  series  in  1895  while  the  700  series 
was  not  cropped.  Besides  the  small  crop  of  1895,  the  yields  in 
1896  were  greater  on  the  600  than  on  the  700  series,  so  that  by 
the  end  of  1896  the  four  plots  mentioned  had  produced  as  an  aver- 
age 39.4  bushels  more  corn  per  acre  on  the  600  series  than  on  the 
700  series. 

But  during  the  next  four  years,  from  1897  to  1900,  previous  to 
the  beginning  of  soil  treatment,  the  700  series  yielded  more  every 
year,  the  average  difference  amounting  to  35.9  bushels  per  acre 
during  the  four  years.  In  other  words,  the  average  difference  of 
39.4  bushels  in  favor  of  series  600  at  the  end  of  1896  had  been  re- 
duced to  only  3.5  bushels  at  the  close  of  1900,  every  one  of  the  four 
plots  having  produced  more  corn  every  year  on  the  700  than  on 
the  600  series,  the  excess  amounting  to  3  bushels  even  in  1900,  thus 
indicating  that  the  remaining  difference  of  3.5  bushels  would  have 
been  wiped  out  in  perhaps  t\vo  more  years. 

The  point  suggested  by  these  data  is,  that  there  is  a  relationship 
between  the  plant  food  to  be  made  available  and  the  crops  possible 
to  be  produced.  The  land  that  was  not  cropped  in  1895  grew 
enough  larger  crops  from  1897  to  1900  so  that  the  five  crops  on 
series  700  practically  equaled  the  six  crops  on  the  600  series.  In 
other  words,  the  plant  food  removed  in  the  1895  crop  apparently 


356  BULLETIN  No.  125.  [May,   1908.} 

reduced  proportionately  the  productive  power  of  the  soil  for  sub- 
sequent crops. 

The  production  of  these  comparatively  large  crops  in  the  early 
years  is  principally  due  to  the  rapid  liberation  of  plant  food  from 
the  decay  of  .fresh  organic  matter  accumulated  in  the  roots  and 
other  residues  of  clover  and  grasses  and  animal  droppings  during 
the  previous  years  of  pasturing;  but  the  lesson  that  is  so  well 
brought  out  in  this  comparison  between  the  600  and  700  series 
during  the  first  few  years  is  a  true  prophesy  of  a  more  important 
lesson  which  applies  to  the  future  years,  to-wit : 

Certain  essential  elements  of  plant  food  (nitrogen  and  phos- 
phorus) are  present  in  limited  quantities  in  the  common  Illinois 
corn  belt  soil,  and  every  crop  removed  with  no  adequate  return 
reduces  to  that  extent  the  power  of  that  soil  to  produce  future  crops. 

NOTE. — For  further  information  concerning  farm  manure,  effect  of  crop 
rotations,  sources  of  plant  food  materials,  methods  of  application,  comparative 
value  of  natural  rock  phosphate,  etc.,  Illinois  readers  are  referred  to  Circular 
108,  "Illinois  Soils  in  Relation  to  Systems  of  Permanent  Agriculture,"  and 
Circular  116,  "Phosphorus  and  Humus  in  Relation  to  Illinois  Soils." 


ir^^»  M  *;&  ! 


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